Black soldier fly as a tool for the valorization of tomato waste

The tomato is one of the most developed horticultural products in Italy and the tomato industry,particularly cannery industry, with 2.5 M tons/y produces enormous quantities of waste for which safe and cost-effective disposal must be developed. In particular, the re-use of washing and sorting residues, consisting of green leaves and stems and defective raw tomatoes (unripe, green or damaged), which represent 2-3% of the weight of the starting material, has been litle studied. In this work, tomato production residues were used as a substrate for the growth of larvae of Hermetia illucens (Diptera: Stratiomyidae), also known as the black soldier fly (BSF), that can grow on numerous organic substrates, converting them into valuable larval biomass rich in proteins and lipids. For this aim, different types of tomato wastes, such as stem, red or green tomatoes, leaves, seeds and peeling waste, were fed to groups of 500 BSF neonate larvae, with three replicates per each experimental trial. Growth parameters, bioconversion and substrate reduction indexes were then evaluated, and the larvae were analyzed to assess their final chemical composition. Results highlighted the ability of BSF to grow on the tomato waste, particularly those consisting of peeling waste (peel and seeds), or here tomato fruits were present in a higher percentage. In order to re-use waste biomass to obtain high added-value products, also in line with the EU's plan on the circular economy, tomato waste deserves further investigation for its exploitation for the production of BSF larvae.